1. Field of the Invention
The present invention relates to a vehicle LED lamp controller and more particularly to a vehicle LED lamp controller providing a safety circuit and used in low temperature environment.
2. Description of Related Art
An LED element has low power consumption and long life term etc. features. Since the white LED element is successfully developed and the LED element, such as red or yellow color LED, has fifty thousand to one hundred thousand-hour life term, the LED elements are wildly used as the light source of the vehicle lamp, recently. However, the brightness of one LED element is not large enough to be a light source of a vehicle lamp. Therefore, the vehicle LED lamp requires multiple LED elements to comply with the standard value of brightness of related vehicle regulation.
To make sure the vehicle LED lamp keeps to work when one or few LED elements are broken, there are three common driving circuits shown in FIGS. 4A to 4C. With first reference to FIG. 4A, the multiple LED elements (LED) are connected in parallel and further connected to one DC power source (+12V). When the DC power source (+12V) is supplied to the multiple LED elements (LED), the vehicle LED lamp will be driven to emit light. If one or few LED elements are broken, other LED elements are still lighted.
With further reference to FIG. 4B, another driving circuit has multiple strings of the LED elements (LED). The strings of the LED elements (LED) are further connected to each other in parallel. The strings of the LED elements (LED) are connected to one DC power source (+12V). When the DC power source (+12V) is supplied to the strings of the LED elements (LED), all strings of the LED elements (LED) emits light. However, if one or few strings of the LED elements (LED) are broken, other strings of the LED elements will emit right.
With reference to FIG. 4C, another conventional driving circuit has multiple LED elements (LED) connected to each other in matrix. Therefore, when one or few LED elements are broken, other LED elements are still bright.
The forgoing three driving circuits respectively ensure that the vehicle LED lamp keeps to light when one or more LED elements are broken, but the brightness of the vehicle LED lamp is decreased. Therefore, these driving circuits are not good enough. In addition, since the operation temperature of the LED element has to be controlled in a specific temperature range to keep work normally, the LED elements are not worked normally when they are used in low temperature environment. Therefore, the vehicle LED lamp is not used wildly in any place of this globe.
Therefore, the present invention provides a controller for a vehicle LED lamp to overcome the drawbacks of the conventional driving circuit of the LED lamp.